(c) A coal-fired power station generates electricity at night when it is not needed.

Is the alien theory a scientific claim? Why or why not?

spin [16.1K]

I'm not sure what the alien Theory says or if there really is such a theory. If the theory says that aliens definitely exist and that they have visited Earth in the past then the theory is totally and completely without any kind of support. It's not scientific in any way because there is no evidence for such a claim. It may be thought to be probable but no solid evidence has ever been presented.

8 0

2 years ago

Read 2 more answers

Helpp me pleassee....

lilavasa [31]

Answer:

The fundamental wavelength of the vibrating string is 1.7 m.

Explanation:

We have,

Velocity of wave on a guitar string is 344 m/s

Length of the guitar string is 85 cm or 0.85 m

It is required to find the fundamental wavelength of the vibrating string. The fundamental frequency on the string is given by :

$f=\dfrac{v}{2l}\\\\f=\dfrac{344}{2\times 0.85}\\\\f=202.35\ Hz$

Now fundamental wavelength is :

$\lambda=\dfrac{v}{f}\\\\\lambda=\dfrac{344}{202.35}\\\\\lambda=1.7\ m$

So, the fundamental wavelength of the vibrating string is 1.7 m.

4 0

2 years ago

Which of the following statements are true? (mark all that apply)

kvv77 [185]

Answer:

(a) and (b)

Explanation:

Energy is the capacity to do work, and exists in various forms. These forms can be converted one to another by the use of appropriate means. Some examples are sound, mechanical, solar, light, which causes the sensation of vision, etc. energy is measured in Joules (J).

The rate of transfer of energy is called power.

i.e Power = $\frac{energy}{time}$

It is measured in Watts (W).

When a white light is disperses into its colors, gray and black are not part of the colors. And a black sometimes could be as a result of the absorption of all other colors of light.

8 0

2 years ago

The atomic radii of Mg2+ and F- ions are 0.072 and 0.133 nm, respectively.(a) Calculate the force of attraction between these tw

timurjin [86]

Answer:

$1.09527\times 10^{-8}\ N$

Explanation:

$q_1$ = Mg ion = $+2q$

$q_2$ = F ion = $-q$

q = Charge of electron = $1.6\times 10^{-19}\ C$

r = Distance between ions = $0.072+0.133\ nm$

k = Coulomb constant = $8.99\times 10^{9}\ Nm^2/C^2$

Electrical force is given by

$F=-\dfrac{kq_1q_2}{r^2}\\\Rightarrow F=-\dfrac{8.99\times 10^9\times 2\times 1.6\times 10^{-19}\times -1\times 1.6\times 10^{-19}}{[(0.072+0.133)\times 10^{-9}]^2}\\\Rightarrow F=1.09527\times 10^{-8}\ N$

The attractive force is $1.09527\times 10^{-8}\ N$

8 0

3 years ago

A piece of wood with density of 824 kg/m^3 is tied to the bottom of a pool and the wood does not move. The volume of the wood is

Reil [10]

Answer:

2069.76 N

Explanation:

density of wood = 824 kg/m^3

density of water = 1000 kg/m^3

Volume of wood = 1.2 m^3

True weight of wood = volume of wood x density of wood x gravity

True weight of wood = 1.2 x 824 x 9.8 = 9690.24 N

Buoyant force acting on wood = volume of wood x density of water x gravity

Buoyant force acting on wood = 1.2 x 1000 x 9.8 = 11760 N

Tension in the rope = Buoyant force - True weight

tension in rope = 11760 - 9690.24 = 2069.76 N

8 0

2 years ago